Lubricated polyolefine ropes



United States Patent 3,420,050 LUBRICATED POLYOLEFINE ROPES Michael Richard Parsey, Edward Thompson, and Eric Walker, Harrogate, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain No Drawing. Filed Aug. 18, 1965, Ser. No. 480,778 Claims priority, application Great Britain, Aug. 31, 1964, 35,528/ 64 US. Cl. 57149 8 Claims Int. Cl. D02g 3/36 ABSTRACT OF THE DISCLOSURE Two to five percent by weight non-drying vegetable oil, such as peanut oil or olive oil, is distributed through a rope constructed of polyolefine yarns, such as polypropylene yarn, to increase the resistance of the rope to fusion and kinking. The oil preferably contains antioxidant stabilizers and may be applied to the filaments at spinning or at any subsequent point in the production of the rope.

This invention relates to ropes made from polyolefine filaments and fibres, having improved properties in use, in particular, having increased resistance to fusion when passed over metal or other solid surfaces at high speeds or under surge loads and having increased resistance to kinking.

The availability of synthetic filaments and fibres in a Wide variety of thicknesses has led to many attempts to utilise their desirable properties, as for example, their high strength and their uniformity, in the production of ropes and like structures. Such attempts have taken the form, for example of the development of special machinery and the treatment of the synthetic fibres with bonding agents and other materials, in order that either the synthetic fibres may be used together with natural cordage fibres or that the wholly synthetic fibre ropes may behave in use like conventional natural fibre ropes.

A particular shortcoming of all synthetic fibre ropes is that they are susceptible to fusion under circumstances of use wherein heat is developed. Another shortcoming of Synthetic fibre ropes is that they frequently do not behave in use like natural fibre ropes; for example synthetic fibre ropes are subject to kinking. Kinking is the effect pro duced by tension which leads to opening of the lay of the rope and production of at least semi-permanent deformations, kinks, of the strands comprising the rope. Kinking resistance may be improved by altering the rope construction, particularly by increasing the strand twist but this leads to an undesirable more open lay which is more susceptible to the collection of extraneous material which may be abrasive and can reduce the life of the rope. Alternatively kinking resistance may be somewhat improved by heat treating the finished rope but this process is costly and time consuming.

We have now found that, when ropes of polyolefine fibres or filaments are being made the application of certain oils during the preparation of the rope or the yarns from which it is constructed increases the resistance to fusion and kinking of the rope in use.

According to the invention we provide ropes made from polyolefine filaments and fibres, having increased resistance to fusion and kinking, characterised in that a non- "ice drying vegetable oil is distributed through the rope structure.

Any polyolefine, from which strong filaments and fibres may be produced may be used in this invention, in particular linear polyethylene and stereoregular polypropylene which already are utilised in the synthetic fibre rope field.

By non-drying vegetable oil is meant an oil which does not readily undergo autoxidation to sticky polymeric products. Preferably the oil should contain antioxidant stabilising substances to further reduce any tendency to autoxidation, especially when spread as a thin film over the parts of the rope structure. Vegetable oils such as peanut and olive oils are very suitable particularly if antioxidant substances are added to the oil.

Ropes prepared according to the invention are much less susceptible to fusion when used under heat producing conditions, particularly under conditions giving rise to sudden surge loads as for example in towing operations. To determine the resistance of ropes to fusion under similar conditions we have tested ropes to destruction using a single barrel (barrel diameter 15 inches) winch applying a torque of 5000 foot/lb. to ropes of 5 inches circumference carrying a load of 24 cwt. The barrel speed used is 12 rpm. and 2 turns of the rope are taken around the winch barrel. The time required for the rope to part is measured.

From tests using 5" circumference ropes made to a standard construction from filaments and fibres of polypropylene which have been treated with mineral oils, silicone oils or oil according to the invention in the foregoing winch test We have found that the optimum improvement of fusion resistance is obtained with oil according to the invention having a viscosity at 25 C. of less than 1500 centipoises and that above a viscosity at 25 C. of about 1500 centipoises the improvement falls off.

Thus according to a further feature of the invention we provide ropes made from filaments and fibres of polypropylene, having increased resistance to fusion, characterised in that a non-drying vegetable oil having a viscosity at 25 C. of up to 1500 centipoises is distributed through the rope structure.

Polyolefine filaments and fibres are usually produced by melt spinning followed by drawing to induce orientation and strength in the filaments, which may then be used directly or cut into fibres for spinning into rope yarns. It is customary to add a small amount of lubricant, usually less than 0.5% by weight, to the filaments at spinning in order that the drawing step, which involves stretching the spun yarn while passing over a snubbing surface, may be facilitated. This lubricant may be an oil according to the invention or an oil of different kind. In either case it is preferred to apply the additional non-drying vegetable oil, required according to the invention, during the drawing step.

In producing ropes according to the invention the nondrying vegetable oil may be used directly or as a solution in a solvent which does not swell the polyolefin fibres and is easily removed by evaporation or as an aqueous emulsion, all of which forms may be applied at any point in the production of the ropes or even to the final rope. In tht latter case, however full penetration of the rope structure may not be obtained thus tending to reduce the improvement of the rope properties. The amount of oil,

its solution or emulsion applied should be sufiicient to obtain the desired enhanced properties in the rope. In general about 25% by weight of the oil in the final rope structure is sufficient for if less than this amount is used little enhancement of rope properties is obtained and if more than this amount is used slippage between the rope and, for example, a winch drum, may occur.

Treatment of ropes with substances not according to the invention usually produces a lowering of the resistance to kinking. However treatment according to this invention with low viscosity, non-drying, vegetable oils does not impair the kinking resistance of polyolefine ropes. We have measured the kinking resistance by means of a device which clamps the ends of a rope specimen 6 inches long under a fixed load of 9 lb. for 1% inches circumference specimens and records the torque required to twist the specimen through 2 revolutions of one clamp in successive steps of 0.5, l, 1.5 and 2 revolutions. The value found after 2 revolutions, is described as the torque resistance of the specimen (measured in inch-pounds) which is found to be proportional to kink resistance in use.

In all tests equivalent rope constructions were used and results were confirmed in full scale towing and other trials.

The following examples, which include some comparative tests, illustrate the improved properties of ropes treated according to the invention.

Example 1 A rope of inches circumference is prepared from 1140 denier isotactic polypropylene filament yarn using 3- strand construction. The yarn had been treated with sufficient undiluted peanut oil containing antioxidants (viscosity at 25 C. of 63.2 centipoises) to leave 3% by weight of the oil distributed in the rope. A similar rope is prepared as a control from 1140 denier isotactic polypropylene yarn which had not been treated with the oil.

Both ropes are heat treated at 140 C. for 15 mins. and

specimen lengths are subjected to the winch fusion test as hereinbefore described. The time required to part the peanut oil treated rope is 187 minutes While only 47 minutes was required to cause the control specimen to part.

Example 2 Example 3 A rope of 3 inches circumference is prepared from a six-ply 6840 denier multifilament polypropylene yarn having 1.75 turns per inch twist. Five percent by weight of the peanut oil composition used in Example 1 is applied at plying and the rope is constructed with a strand angle after hardening of 33 and a rope angle of 27". A splice breaking test and an abrasion test are carried out on the rope and comparison tests using a 3 inch circumference rope of the same construction but not treated with the vegetable oil are also made. For the splice tests a 4-tuck splice is made in each rope and a Dennison horizontal rope tester 0f 50 tons capacity is used. For the abrasion tests the ropes under a load of 28 lbs. are led at an angle of 90 over a mild steel bar of 0.5 inch diameter and oscillated with a stroke of 18 inches at a frequency of 25 cycles per minute until broken.

Rope of 6 inches circumference is made in an 8-strand plaited construction using as the centre rope yarn in each strand a polypropylene filamentary yarn treated with the vegetable oil used in Example 1 and untreated polypropylene yarns for the remainder. The splice breaking load of the rope is 12% greater than an identical rope constructed without vegetable oil treatment.

Example 5 Forty-five feet lengths of rope of 3" circumference, constructed from 40" x 0.005" polypropylene fibres (having 3% by weight of peanut oil with antioxidants thereon) on the normal hard fibre ropemaking machinery, are used to make endless rope slings which are employed for loading bagged soda ash by crane during 64 hours per week, each sling being in use every 5 minutes. Identical slings made from rope not treated with the vegetable oil are used for the same service as controls.

The improved service obtained from slings made of ropes according to the invention is illustrated by the following values of breaking load at the point of maximum abrasion and of average breaking load.

Breaking load (tons) At point of max. Average abrasion Vegetable oil treated rope 3. 7 5. Control rope 2. 65 4. 3

Comparative examples For comparison the efiect on torque resistance of several diiferent types of conventional materials is as follows. In all cases isotactic polypropylene ropes of 1% inches circumference were used as in Example 2.

Material Percent by weight Torque resistance of material (in.-1b.)

Poly(ethylene oxide) M.W.=6O 4 12.8 Poly(ethylene oxide) (M.W.=400) end stopped with a fatty acid. 4. 5 10. 5 Silicone oil (60,000 centipoises) 5 10. 8

4. Ropes according to claim 3 wherein the vegetable oil is selected [from the group consisting of peanut oil and olive oil.

5. Ropes according to claim 1 wherein the oil is present in the range 25% by weight.

6. Ropes according to claim 5 wherein up to .5 by weight of another lubricant is present in addition to the vegetable oil.

7. Ropes according to claim 1 wherein the polyolefine is selected from the group consisting of linear polyethylene and stereoregular polypropylene.

8. A rope structure composed of a plurality of polyolefine yarns, said rope having increased resistance to fusion and kinking due to the presence of 2-5 by weight of a non-drying vegetable oil having low autoxidation properties, said oil being distributed through the rope structure as a film on the parts of the rope structure.

References Cited UNITED STATES PATENTS Hodson. Howell.

Rick. Sommerville. Simpson. Stanton. Dawbarn et a1. Stirling.

Great Britain.

US. Cl. X.R. 

